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SubjectRe: [PATCH -rt] ARM TLB flush fix: don't forget to re-enable preemption
On Tue, May 22, 2007 at 04:41:36PM -0700, Kevin Hilman wrote:
> On Tue, 2007-05-22 at 16:25 -0700, Daniel Walker wrote:
> > On Tue, 2007-05-22 at 16:01 -0700, Kevin Hilman wrote:
> > > Add a preempt_enable() to flush_tlb_kernel_page() since -rt4 patch
> > > adds a preempt_disable but no preempt_enable().
> > >
> > > Signed-off-by: Kevin Hilman <khilman@mvista.com>
> > >
> > >
> > > ---
> > > include/asm-arm/tlbflush.h | 1 +
> > > 1 file changed, 1 insertion(+)
> > >
> > > Index: linux-2.6.21/include/asm-arm/tlbflush.h
> > > ===================================================================
> > > --- linux-2.6.21.orig/include/asm-arm/tlbflush.h
> > > +++ linux-2.6.21/include/asm-arm/tlbflush.h
> > > @@ -378,6 +378,7 @@ static inline void local_flush_tlb_kerne
> > > asm("mcr p15, 0, %0, c8, c6, 1" : : "r" (kaddr) : "cc");
> > > if (tlb_flag(TLB_V6_I_PAGE))
> > > asm("mcr p15, 0, %0, c8, c5, 1" : : "r" (kaddr) : "cc");
> >
> > Aren't these mcr operations atomic?
> >
>
> Individually, yes. But the point of the preempt_disable/enable is to
> make the whole sequence atomic.

In which case shouldn't it be at the end of the function so it includes
the write buffer handling as well?

However, I think I agree with Daniel on this one. I don't see the point
of the preempt_disable() here.

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of:
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